The season 6 premiere of "Rick and Morty," "Solaricks," is one of those rarer episodes. It resolves the cliffhanger that ended season 5 fairly quickly. In a send-up of "Avengers: Infinity War," Rick and Morty are rescued from the destroyed Council of Ricks citadel by Space Beth, the galaxy-traveling clone (or not) of Beth Smith. Once they get home, Rick has to reset his portal gun navigation but winds up sending its users (himself, Morty, and Jerry) to their original universes.

Building on his backstory from the season 5 finale, Rick goes to the universe where his wife Diane and his original Beth were killed; a virtual recreation of Diane's voice passive-aggressively taunts him. Jerry, who it turns out was swapped at the daycare in season 2's "Mortynight Run," goes to a universe where he and Beth never separated. Morty goes to the show's original "main" universe, the one which was left in ruin at the end of season 1's midpoint, "Rick Potion #9."

Here's how Morty's original home has changed, and why "Rick Potion #9" remains one of the series' most important episodes.

A Tone-Setting Twist

The sixth episode of "Rick and Morty" season 1, "Rick Potion #9," is titled after the love potion that Morty asks his grandfather to make for him (the ingredients are Morty's DNA and oxytocin extracted from a vole). Morty, the little perv that he is, uses the drug to make his crush Jessica fall for him. Unfortunately, because Jessica has the flu, the serum's effects go airborne. Before long, a crowd is willing to tear Morty apart just to get a piece of him.

Rick tries to create a cure by using praying mantis DNA since that species kills its partner after mating (which Rick reasons is the opposite of voles, who mate for life). Unfortunately, all that does is turn everyone into human-mantis hybrids that want to make love to Morty and then bite his head off. Rick's next attempt turns everyone into monstrous, "Cronenberg" monsters. Rick decides to cut his losses and takes Morty to another dimension where they solved the problem then died immediately afterwards. They bury their counterparts in the Smith family backyard and assume their places, with the original Jerry, Beth, and Summer left behind.

This ending is a very dark spin on one of TV's cardinal rules: that everything goes back to normal at the end of the episode. "Rick Potion #9" is the boldest episode of season 1. After five standalone episodes, the viewer expects the episode to just be another adventure, which is why the ending is so audacious. It also shows the dark depths of Rick's nihilism. Morty is horrified by the events, but Rick's advice is to just not think about it; the infinite number of universes means their actions are nothing on the cosmic scale.

A Return Home

"Rick Potion #9" was first revisited in the "Rick and Morty" season 3 premiere, when Morty took Summer to visit his old universe. Morty's original family was still alive, but seemingly feral. Agents of the Council of Ricks arrived and froze the "Cronenberg" Smiths while taking Morty and Summer.

That was the last we saw of the universe until "Solaricks." Morty makes his way home and finds that Jerry is the only Smith left; Beth and Summer died from hypothermia after they unfroze. Back in "Rick Potion #9," Beth and Jerry's marriage had been saved by Jerry becoming a much more manly (albeit still dense) mutant slayer. That happiness didn't last, but Jerry was able to bury his grief thanks to some scavenged self-help books (plus "The Dark Knight Returns.") Jerry is so self-reliant, in fact, that he steals from Morty and abandons his son.

Meanwhile, Rick manages to build a new ship while both Beths and Summer reset the Citadel's portal navigation. While rescuing Morty, Rick discovers that the Rick who killed his Beth and Diane is the Rick from Morty's native universe — but at Morty's urging, he stalls his revenge to help save both Beths and Summer from an alien attack.

When the Smiths get home, they discover the alternate Jerry transported to their universe. He frees an alien called "Mr. Frundles," who engulfs the Earth. The episode comes full circle as the whole family pulls the same trick that ended "Rick Potion #9." Their options for replacement universes are limited, so Rick settles for one where Parmesan is pronounced, "Par-mee-see-an."

In the episode's post-credit scene, "killer Rick" meets (and kills) "Cronenberg Jerry." It's unclear if the show will ever revisit the Cronenberg universe again, but a showdown between the two Ricks seems inevitable.

Read this next: The 15 Best Rick And Morty Villains Ranked

The post The Rick And Morty Season 6 Premiere Revisits One Of The Show's Most Important Episodes appeared first on /Film.